1. Field of the Invention:
The present invention relates to an index device for indexing a rotatable magazine having a plurality of tool holding devices to a predetermined tool change position for a tool exchange operation.
2. Description of the Prior Art:
For indexing a rotatable magazine provided with a plurality of tool holding devices being addressed in a numerical order to a predetermined tool change position, an index signal is generated each time each tool holding device is indexed to the tool change position. An up-down counter counts the index signal in order to distinguish an address of the tool holding device indexed to the tool change position. When the content of the counter coincides with a commanded address, rotation of the magazine is stopped to position the tool holding device having the command address at the tool change position. However, if the counter miscounts the index signal, the address of the tool holding device having been indexed to the tool change position does not coincide with the content of the counter. Accordingly, an incorrect tool holding device is indexed to the tool change position and the malfunction is overlooked.